From owner-freebsd-xen@FreeBSD.ORG Tue Apr 14 13:31:46 2015 Return-Path: Delivered-To: freebsd-xen@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 84E33A16 for ; Tue, 14 Apr 2015 13:31:46 +0000 (UTC) Received: from dash.upc.es (dash.upc.es [147.83.2.50]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "relay.upc.es", Issuer "TERENA SSL CA" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id E7E85D5 for ; Tue, 14 Apr 2015 13:31:45 +0000 (UTC) Received: from ackerman2.upc.es (ackerman2.upc.es [147.83.2.244]) by dash.upc.es (8.14.1/8.13.1) with ESMTP id t3EDVfds032151 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES128-SHA bits=128 verify=FAIL) for ; Tue, 14 Apr 2015 15:31:42 +0200 Received: from [10.0.2.151] ([147.83.40.10]) (authenticated bits=0) by ackerman2.upc.es (8.14.4/8.14.4) with ESMTP id t3EDVf2h016022 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES128-SHA bits=128 verify=NO) for ; Tue, 14 Apr 2015 15:31:41 +0200 Message-ID: <552D16BD.5060603@entel.upc.edu> Date: Tue, 14 Apr 2015 15:31:41 +0200 From: =?UTF-8?B?R3VzdGF1IFDDqXJleg==?= User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 MIME-Version: 1.0 To: freebsd-xen@freebsd.org Subject: Setting the right mtu when creating a domain Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.4.3 (dash.upc.es [147.83.2.50]); Tue, 14 Apr 2015 15:31:42 +0200 (CEST) X-Greylist: Default is to whitelist mail, not delayed by milter-greylist-4.4.3 (ackerman2.upc.es [147.83.2.244]); Tue, 14 Apr 2015 15:31:41 +0200 (CEST) X-Scanned-By: MIMEDefang 2.70 on 147.83.2.244 X-Mail-Scanned: Criba 2.0 + Clamd X-BeenThere: freebsd-xen@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: Discussion of the freebsd port to xen - implementation and usage List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 14 Apr 2015 13:31:46 -0000 Hi, the box I'm doing testing with has all its interfaces set with mtu 9000. That is a problem at domain creation time, because taps are set to 1500, and bridge [1] is created with the mtu of the first interface added. So if you're using an mtu different than 1500 (it could also be less than 1500 for any special reason) in an interface part of the bridge (and thus the bridge will have mtu != 1500) that would cause problems with the tap of the new domain. I did a simple patch to tools/hotplug/FreeBSD/vif-bridge to get the bridge mtu and create the tap with the right mtu [2]. I'm not sure if this can be accomplished somewhere else, but I thought this way the bridge can be configured in rc.conf and our vif-bridge may be able to fetch the right mtu. Nothing from ports is used (sed from base system). Best, G. [1] man 4 bridge [2] http://dpaste.com/2HN8SHN